The Genetic Diversity Of Plasmodium Falciparum In Ghana

ABSTRACT

Background

The population structure of the causative agents of human malaria, Plasmodium species including the most serious agent Plasmodium falciparum, depends on the local epidemiological and demographic situations, such as the incidence of infected people, the vector transmission intensity and migration of inhabitants (i.e. exchange between sites).One of the major characteristics of malaria parasites is their genetic diversity and an increasing number of studies have reported on the population structure variation of P. falciparum. Genetic diversity and population structure of P. falciparum is required in predicting the origin and spread of novel variants within a population enabling specific malaria control measures in the era of intensive malaria intervention strategies.

Aim

This study investigated the genetic diversity of P. falciparum in sites with different malaria endemicity in Ghana.

Methods

Finger prick blood samples were made from primary school children in five study sites in Ghana. This was carried out during the dry (March) and rainy (July) seasons of 2017. The samples were collected on filter paper and on slides and examined for parasite detection using light microscopy (LM), and molecular diagnosis (18s rRNA nested PCR). The positive P. falciparum samples were characterized using microsatellite markers.

Results:

Light microscopy showed the highest prevalence in the Duase during the rainy season with 24.1%. Kpasolgu during the dry season sampling exhibited the lowest prevalence of P. falciparum parasites with 7.1%. The southern sites, Anyakpor and Odumase showed an

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intermediary prevalence of 12.8% and 16.9% respectively in the rainy season. This was the highest prevalence between the rainy and dry seasons in the southern sites. The sites Pagaza and Kpalsogu found in the northern part of Ghana, the Sahel savannah zone presented 17.7% and 18.2% prevalence respectively. This is according to light microscopy. Nested PCR detected a higher level of parasites in all samples. Duase in the Forest zone showed the highest prevalence, 58.8% in the samples collected in the rainy season. The Forest zone exhibited 9.8% indicating the lowest prevalence among the sites from the samples obtained in the dry season in Duase. This affirms that PCR is a more sensitive tool of detection of parasites in determining the parasite carriage. In determining the variation in diversity, genetic differentiations in the different sites tested were observed. There was a higher genetic diversity evidenced by the highest frequency of heterozygosity in the Northern region.

Conclusion

In this study, little significant differentiation in the genetic diversity was observed between the different ecological zones in Ghana. This reveals a range of population structures within the species of P. falciparum and suggests how genetic variation impacts the epidemiology and control measures between different transmission zones in Ghana.